Superabsorbent materials have found particular utility in tampons because of their ability to rapidly absorb large volumes of material in a relatively short time. Due to the relatively small size of a tampon compared to a sanitary napkin, absorption per unit volume can be a critical feature in measuring the performance of the tampon. For purposes of this invention a superabsorbent is defined as a material which may be either fibrous or nonfibrous in form but which develops capillary suction pressure of at least 25 centimeters of water when a gram of such material has absorbed 5 milliliters of physiological saline solution.
It is well known, however, that there are problems associated with the presence of superabsorbent material in tampons. Particularly acute is the difficulty associated with withdrawal of tampons containing superabsorbent material. Due to the rapid uptake of fluid by superabsorbent material a negative or suction pressure is built up on the surface. If this material is allowed to contact the walls of the vagina or be in close proximity thereto, withdrawal entails a physical force needed to separate the suction forces exerted on the walls of the vagina from the source of the pressure i.e. the superabsorbent.
There have been several attempts in the past to provide means for utilizing the superabsorbent capacity while minimizing the affect of the superabsorbent derived capillary suction. South African Patent No. 77/3309, for example, discloses a tampon in which a superabsorbent is wrapped in tissue and a nonwoven wrap. U.S. Pat. No. 4,056,103 discloses utilizing a wrap which will retain some measure of fluid to act as a lubricant. Attempts have been made to apply emollient coatings which are fluid and water soluble to a wrapped tampon to minimize the effect of the negative suction pressure. Additionally, it is known to utilize a mixture of superabsorbent and conventional cellulosic absorbents in an attempt to minimize the suction pressure associated with superabsorbents.
It is also known to utilize water soluble film in conjunction with a tampon. U.S. Pat. No. 3,371,666 discloses a tampon having a multiplicity of layers of two different types. One of the types of layers alternating with conventional absorbents is a thin water soluble film such as carboxymethylcellulose which itself acts as an absorbent component.